Mycorrhizae: Description of Types, Benefits and Uses - Greenhouse Product News
Abstract: There are two types of mycorrhizae: ectomycorrhizae and endomycorrhizae. Ectomycorrhizae form an extensive dense sheath around the roots, called. They form a close symbiotic relationship with plant roots. They are called mycorrhizae from the Greek "mukés", meaning fungus, and "rhiza," meaning roots . Describe the symbiotic relationship of mycorrhizae and plant roots In endomycorrhizae, mycelium is embedded within the root tissue.
Orchid mycorrhiza All orchids are myco-heterotrophic at some stage during their lifecycle and form orchid mycorrhizas with a range of basidiomycete fungi.
In such a relationship, both the plants themselves and those parts of the roots that host the fungi, are said to be mycorrhizal. The Orchidaceae are notorious as a family in which the absence of the correct mycorrhizae is fatal even to germinating seeds. This relationship was noted when mycorrhizal fungi were unexpectedly found to be hoarding nitrogen from plant roots in times of nitrogen scarcity.
Researchers argue that some mycorrhizae distribute nutrients based upon the environment with surrounding plants and other mycorrhizae. They go on to explain how this updated model could explain why mycorrhizae do not alleviate plant nitrogen limitation, and why plants can switch abruptly from a mixed strategy with both mycorrhizal and nonmycorrhizal roots to a purely mycorrhizal strategy as soil nitrogen availability declines.
On the right side of this diagram, the arbuscular mycorrhiza pathway, which branches off from the plant root, which is the brown cylinder-like figure in the image, provides the plant with nutrients, including, most importantly, phosphate and nitrogen. My reference source for this information is: In return, the plant gains the benefits of the mycelium 's higher absorptive capacity for water and mineral nutrients, partly because of the large surface area of fungal hyphae, which are much longer and finer than plant root hairsand partly because some such fungi can mobilize soil minerals unavailable to the plants' roots.
The effect is thus to improve the plant's mineral absorption capabilities. One form of such immobilization occurs in soil with high clay content, or soils with a strongly basic pH.
The difference between ENDO and ECTO Mycorrhiza. | aurea
The mycelium of the mycorrhizal fungus can, however, access many such nutrient sources, and make them available to the plants they colonize. Another form of immobilisation is when nutrients are locked up in organic matter that is slow to decay, such as wood, and some mycorrhizal fungi act directly as decay organisms, mobilising the nutrients and passing some onto the host plants; for example, in some dystrophic forests, large amounts of phosphate and other nutrients are taken up by mycorrhizal hyphae acting directly on leaf litter, bypassing the need for soil uptake.
These structures have been shown to host nitrogen fixing bacteria which contribute a significant amount of nitrogen and allow the pines to colonize nutrient-poor sites.
Physically, most mycorrhizal mycelia are much smaller in diameter than the smallest root or root hair, and thus can explore soil material that roots and root hairs cannot reach, and provide a larger surface area for absorption. Chemically, the cell membrane chemistry of fungi differs from that of plants.
For example, they may secrete organic acid that dissolve or chelate many ions, or release them from minerals by ion exchange.
These associations have been found to assist in plant defense both above and belowground. Glossary Mycorrhizal types Mycorrhizas were traditionally classified into the two types: This classification is now regarded as too simplistic, and there is now a nomenclature identifying seven mycorrhizal types; however we will telescope this into four major types with three additional subclasses as follows click on on the blue hyperlinked names in this text to open a new page giving more information on all seven types of mycorrhiza: Endomycorrhizas, in which the fungal structure is almost entirely within the host root, comprising three major and two minor groupings: The AM association is endotrophic, and has previously been referred to as vesicular-arbuscular mycorrhiza VAM.
Ericoid endomycorrhizas are mycorrhizas of Erica heatherCalluna ling and Vaccinium bilberrythat is, plants that endure moorlands and similar challenging environments.
Fungi are members of the Ascomycota an example is Hymenoscyphus ericae. Two specialised subgroups may be separated out of the ericoid endomycorrhizal group: Arbutoid endomycorrhizasand Monotropoid endomycorrhizas the mycorrhizal association formed by the achlorophyllous plants of the Montropaceae. Orchidaceous endomycorrhizas are similar to ericoid mycorrhizas but their carbon nutrition even is more dedicated to supporting the host plant as the young orchid seedling is non-photosynthetic and depends on the fungus partner utilising complex carbon sources in the soil, and making carbohydrates available to the young orchid.What do Endo and Ecto Mycorrhizae Do in The Garden & What's The Difference?
All orchids are achlorophyllous in the early seedling stages, but usually chlorophyllous as adults, so in this case the seedling stage orchid can be interpreted as parasitising the fungus. A characteristic fungus example is the basidiomycete genus Rhizoctonia although this is a complex genus which can be divided into several new genera. The hyphae penetrate between the outermost cell layers forming what is called the Hartig net Fig.